Translating and rotation micro mechanisms can be used in many applications such as adaptive optics for wavefront corrections, spatial light modulation, micro endoscopic confocal imaging, positioning micro lenses for auto focusing/zooming, aligning optical components, micromanipulators or micro stages. Most of these applications require a large out-of-plane translation or rotation or both, e.g., more than 10 μm is needed for adaptive optics modules used in large size ground telescopes, more than 20 μm is needed for wavefront corrections in adaptive optics modules used in vision science, and several tens to several hundred micrometers are needed for positioning micro lenses for auto focusing/zooming, alignment of optical devices, micro manipulators, micro stages, optical coherence tomography and confocal microscopy imaging applications, and several degrees of rotation in 2D is needed for imaging and display applications.
Various micro mechanisms were developed in order to achieve a large out-of-plane translation and rotation. These include those designs based on micro electrostatic actuators, exemplified by a device by V. Milanovic et al. (published in IEEE Photonics Technology Letters, Vol. 16, pp. 1891-1893, 2004), electrothermal actuators, exemplified by a device designed by A. Jain and H. Xie (published in IEEE Journal of Selected Topics in Quantum Electronics, Vol. 13, pp. 228-234, 2007), and electromagnetic actuators, exemplified by a device by I-J Cho and E. Yoon (published in J. Micromech. Microeng. Vol. 19, pp. 1-8, 2009).
Micro electrothermal actuator based designs have achieved out-of-plane translation of several hundred micrometers. However, electrothermal actuator based designs require high power (10s˜100s mW), are slow to respond and have low accuracy. Electromagnetic actuator based designs have achieved an out-of-plane translation of 84 μm. Drawbacks of electromagnetic designs include high power consumption, e.g., 100s mW and difficulty in fabrication of the magnetic thin films or the need for an external magnetic field. Compared with micro electrothermal and electromagnetic actuator based designs, micro electrostatic actuator based designs offer much lower power consumption (less than 1 mW or even zero power consumption when used for maintaining a static position), fast response, high accuracy and high compatibility with CMOS fabrication technologies. However, it is very challenging to achieve a large out-of-plane translation and rotation using electrostatic actuators. A number of micro electrostatic actuators have been developed in order to lead to a larger out-of-plane displacement. For example, an out-of-plane translation of 5 μm was achieved by the actuator presented by F. Pardo et al., (published in the Journal of Microelectronic Engineering, Vol. 84, pp. 1157-1161, 2007), which used in-plane comb-drive actuators whose rotation was converted into an out-of-plane translation. The design presented by M. A. Helmbrecht, et al. (published in the Proc. SPIE, Vol. 6223, 2006, pp. 622305.1-622305.7) is a parallel-plate actuator which achieved an out-of-plane translation of 7.5 μm by raising the moving electrode using the residual stress in order to obtain a large initial gap. A micro electrostatic actuator presented by V. Milanovic, et al. (published in IEEE Journal of Selected Topics in Quantum Electronics, Vol. 10, pp. 462-471, 462-471, 2004) achieved an out-of-plane translation of 60 μm. This actuator utilized a vertical comb-drive structure plus a rotation transformer mechanism. The actuator was fabricated using front and back side etching of an SOI wafer.
In light of the foregoing discussion, there is a need for a micro translating and rotation actuator device with large translation and rotation capabilities.